In front of you are two boxes.
Box A contains $1000.
If Omega predicted you would just take Box B, Box B contains $1,000,000.
If Omega predicted you would take both boxes, Box B contains nothing. Omega will also go back in time and kill your grandfather.
Nobody has any idea how accurate Omega's predictions are.
Does the fact that you exist prove that Omega thought you would just take one box, so Box B definitely contains the million dollars, and if you took both boxes it would imply that Omega was a terrible predictor so you might as well just take both boxes and run?